1. Field
Various embodiments of the present disclosure relate to electronic apparatuses and methods of controlling the same.
2. Related Art
A photographing apparatus, such as a digital camera or a video camera, obtains photographed image data of a subject by forming a subject image on an image sensor. The image sensor may receive incident light through an optical system including a photographing lens and a hand trembling compensating unit.
The hand trembling compensating unit is provided in the photographing apparatus to prevent image shaking caused by hand trembling. For example, when a pose or orientation change of the digital camera is detected by a sensor such as a gyro sensor, a position of a dedicated compensation optical system or the image sensor is slightly shifted to offset image shaking caused by hand trembling.
Also, in the image sensor, a noise signal referred to as a dark current is generated due to temperature even in a darkened state (e.g., when receiving low levels of incident light). Thus, since a fixed pattern noise caused by the dark current is superimposed on photographed image data read from an effective pixel region of the image sensor, a black level of an image increases.
In this case, a color reproduction level of the subject image in the photographed image data decreases. Thus, the fixed pattern noise is suppressed by subtracting the photographed image data (dark current) of the image sensor in a shaded state (dark state) from the photographed image data captured for an image.
In some dark current subtracting methods, when photographed image data obtained by photographing a subject image and photographed image data photographed in a dark state are analog-to-digital (A/D) converted, an error in the energy of both dark current components occurs in a quantization process. Thus, since a fixed pattern noise may not be sufficiently removed from the photographed image data even by dark current subtraction, fixed pattern noise may remain in the photographed image data obtained by photographing the subject image.
For example, when dark current subtraction processing is performed, a result as presented in Equation 1 below may occur, wherein I denotes a signal intensity of a photographed image, ad denotes a deviation from a dark current, and σd' denotes a deviation after dark current subtraction processing.(σd′)2=σd2+σd2σd′=21/2σd S/N′=I(21/2σd)   [Equation 1]
That is, when dark current subtracting processing is performed according to Equation 1, the energy of the fixed pattern noise of the photographed image decreases, but the deviation increases.